Re: bnfclgp

[Igor Schein <igor@txc.com>]

On Fri, Aug 20, 1999 at 03:28:52PM +0100, Kevin Buzzard wrote:
> Q3 [finally on topic]: the loop above gets stuck at d=-288.
> 
> bnfclgp(-288)

??quadclassunit
quadclassunit(D,{flag = 0},{tech = []}):

   Buchmann-McCurley's  sub-exponential  algorithm  for computing the
class group of a quadratic field of discriminant  D.   If D is not
fundamental,  the result is undefined,  but usually correct  (a
warning is issued). The more general function bnrinit should be used
to compute the class group of an order. 

So the result is undefined for non-fundamental discriminants, and
that's why you're hitting infinite loop.

I usually do it something like this:

for(k=2,N,if(isfundamental(k),print(k," ",quadclassunit(k)),))

Igor